WIMBLEDON, England – Few juniors have a lot of grass-court experience. In fact, not that many pros do either, as the season on turf only lasts five weeks.

But four U.S. juniors were loving the lawns on Wednesday when Stefan Kozlov, Taylor Townsend, Louisa Chirco and Jamie Loeb all won their matches in impressive fashion.

Just 15, Kozlov overcame his nerves after a one-sided first set against the tall German Alexander Zverev to earn a 1-6, 6-4, 4-0 victory, after Zverev retired. Townsend, 17, thumped Swiss Karin Kennel, 6-3, 7-5; Chirco, 17, won a marathon match over Czech Katerina Siniakova, 4-6, 7-4 6-4; while Loeb, 18, also had to go a long three sets to dispatch Italy’s Alice Matteucci, 6-7(5) 6-2 6-3.

Kozlov, Townsend and Chirco all work under USTA Player Development coaching, while Loeb works out of New York’s John McEnroe Academy.

Though Kozlov isn’t very tall, he is thickly muscled for his age, moves quite well, has a strong first serve and forehand. He’s working on coming to the net more, but from the backcourt he's extremely solid and can also mix things up, sporting a flat two-handed backhand as well as a nifty slice one-hander that he frequently employs.

"That was the most nervous I’ve ever been," said Kozlov, who will play Britain’s Kyle Edmund, the fifth seed, in the next round. "I came back [on court] not worrying about it as much because in the first set I was really tight. I played him two years ago and it was 6-1 6-1, and I knew he was looking for revenge. He’s been playing well the past couple weeks."

Kozlov, who was born in Macedonia but moved to the United States when he was just 1, has been playing since the age of 4 when his father began teaching him the game. He currently practices the USTA National Training Center in Boca Raton, Fla., and is coached by the USTA’s Nicolas Todero.

"It’s working well," Kozlov said. "It’s a great atmosphere. I’ve got a lot of good people around me. There’s a lot of great players there, so good practices."

Chirico, Townsend and Loeb all played for the U.S. team that beat Britain at the Maureen Connolly Cup three weeks ago. Chirico, who reached the Roland Garros junior semifinals, didn’t even step on grass until the week after she left Paris, when she traveled with Townsend, Melanie Oudin and USTA coach Jay Gooding to the WTA event in Birmingham, England, where the juniors practiced, but did not compete.

"It was so fast and I was l stunned," said the New Yorker Chirico of the grass. "The grass is thin. I can use my serve and be aggressive. I can hit through the court and I get a little more out of it than I do on clay."

The teenagers are getting a taste of what the pro tour lifestyle is like. They have been in Europe for a long time, and as such they’ve grown closer. Chirico and Townsend are roommates, which help them both avoid homesickness. And they’ve been able to observe how the top pros go about their career at tournaments such as the Connolly Cup in Birmingham and also in Eastborne, not to mention Roland Garros and Wimbeldon.

"To see how disciplined they are on the road, tournament to tournament and to get insight and say I am doing that, keep working at it and hopefully it will pay off," said Townsend, who finished 2012 as the world's No. 1 junior girl. "It’s great to see how intense and strict they are on themselves. In practice people snap racquets and get pissed but that doesn’t happen in their matches. You know they are hard on themselves. It shows some of the characteristics these pros have in common."

Like all of the U.S. juniors, the left-handed Townsend, who last year won the Australian Open juniors in singles and the Australian Open, Wimbledon and the US Open in doubles, has taken to the grass surface. In her victory on Wednesday she could be seen serve and volleying, which is unusual in the junior ranks if not as much for the all-courter Townsend.

"I love the grass. I have fun," said Townsend, who will face fourth seed Barbora Krejcikova of the Czech Republic in the quarterfinals. "It really suits my game and helps my all-court game, my transition game and to get to the net more."

Loeb was thrilled with her victory as it’s the furthest she has advanced in a junior Grand Slam. She played a number of USTA Pro Circuit events this year to some success, so when she entered Wimbledon she felt like she was better all-around player.

"It’s a very big accomplishment for me and really brings my confidence up," said Loeb, who has the pleasure of facing top seed Belinda Bencic in the quarterfinals.

Loeb is from a tennis family. She’s the baby of her family by a long shot. Her older sister Jenna, who was three-time New York state high school girls champ, is nine years older than her, and her two brothers are both in their 30s. Jenna ended up playing for Wake Forest and Jamie will attend and play for the University of North Carolina beginning in the fall, with future plans to turn pro.

Loeb has playing out of the McEnroe Academy for about two years and is coached by Felix Alvarado. She has hit a number of times with John, who came out to watch her first two matches at Wimbledon, a locale where he raised the big trophy three times.

At first she was a little intimidated.

"He’s very intense and he still gets very mad at himself," she said. "But he’s great and I enjoy to listening to what he has to say because we think a little differently."

John McEnroe is actually advising Loeb to take a different attitude than he did to court. It seems like the notoriously temperamental seven-time Grand Slam champion has learned his lesson, or at least wants to impart it to others.

"He tells me when I play not to be too hard on myself because I tend to," she said with a laugh. "And he still does it with himself. It works for him, but it doesn't for everybody. He lets it out, which works for him, but for other people it’s negative. But tactically he sees tennis as a chess game and that helps a lot."